The damage of cell membrane leads to the release of cytoplasmic enzymes. The measurement of released cytoplasmic lactate dehydrogenase (LDH) is a well-accepted assay to estimate cell membrane integrity and quantify cytotoxicity.

The SensoLyte® Cell Cytotoxicity Assay Kit uses resazurin as a sensitive fluorogenic indicator (Ex/Em=560 nm/590 nm upon conversion) to measure LDH activity. The assay can be performed in a mixed population of damaged and viable cells, but it only measures the LDH released from damaged cells. The cytoplasmic LDH in living cells produces little signals under assay condition. There is no need for extra steps to separate living cells and supernatant. The fluorescent signal is proportional to the number of damaged cells (up to 2.5X104 cell, r2>0.95) with the detection limit reaching 100 dead cells. The kit is suitable for high throughput screening of cytotoxicity of a variety of compounds. 384-well or 1536-well format can be used with minor modifications.